Is this overflowing post box telling a thief that they are unlikely to be disturbed?
It used to be easier when I was young as we knew our neighbours and we could ask someone to check the mailbox.
Otherwise we could get a family member to call round every 2-3 days.
These day people seem more mobile and may not live in the same state, or in my case, the same country as relatives.
Working long hours and driving everywhere many people don’t really know their next door neighbour!
Rather than get the cheapest and smallest post box when you move in perhaps you should think about a box Big Enough for several days post (and Junk Mail)
See Letter Boxes and Numbers for more posts